How do different physical settings impact tabletop sessions?

Typically, I've setup most game environments for tabletop RPG with the typical table (usually enough to seat 4-6 participants) and chairs.

A few times I've had games in a more relaxed setting, a couple of couches and a coffee table.

A few months ago I watched (yet another) mockudrama about role-playing gamers, and they actually gathered on the floor, sitting on various cushions and the like.

I wonder how these different setting impact the comfort level vs. focus of gamers?

Does the more comfortable couch or cushions setting let people focus more on the game because they are comfortable, or do they tend to lose focus more? After some baselines are established with the standard tabletop setting, it would be interesting to run some tests with the other settings.

Any thoughts or experiences from others regarding this?

Lighting variables, sound variables, olfactory variables, seating variables, table/battlemats (if applicable) variables, temperature variables, etc. :-)